Spirocyclic quaternary nitrogen compounds as silver halide sensitizers



United States Patent O Int. Cl. Gioc 1/28 U.S. Cl. 96-107 6 Claims ABSTRACT OF THE DISCLOSURE Photographic silver halide emulsions having their sensitivity increased by the addition of a compound having the formula:

in which X is a single chemical bond, a sulfur atom, a methylene group, a sulfonyl group or the quaternary nitrogen atom of a spirocyclically bound thiomorpholine ring, and A is any anion including a tosylate anion. Other sensitizers can be added as well as stabilizers.

The present invention relates to photographic silver halide emulsions chemically sensitized by the addition of heterocyclic sulfur compounds.

A number of methods have been described for improving the sensitivity of photographic silver halide emulsions other than by optical or spectral sensitization through the incorporation of certain sensitizing dyes in the emulsion. The incorporation of such dyes in the emulsion increases the optical or spectral range of sensitivity, and for this reason such dyes are commonly referred to as optical or spectral sensitizing dyes. Contrary to such optical or spectral sensitizers the so-called chemical sensitizers are believed to react with silver halide to form on the surface of the silver halide grain, sensitivity specks the chemical nature of which depends on the kind of the chemical sensitizer. The sensitivity of silver halide emulsions can be increased by chemical ripening or afterripening during the preparation of the emulsion, by either prolonging the ripening time or by the addition of suitable substances such as compounds of noble metals or thiosulfate or other sulfur compounds. According to another method customarily employed the sensitivity of a photographic emulsion can be increased by the addition of development accelerators or chemical sensitizers to the emulsion, usually when it is completely ripened.

Suitable development accelerators are, for example, compounds containing onium groups (for example, quaternary ammonium or phosphonium and ternary sulfonium salts) and polyalkylene oxides and derivatives of polyalkylene oxides.

The process of chemical sensitization, however, reaches a limit beyond which further addition of sensitizing compounds or of prolonged digestion in the presence of a sensitizer, merely increases the undesired fog of the photographic emulsions.

In particular with respect to polyalkylene oxide sensitizers, many attempts have been made to increase the sensitizing action by modifying the chemical structure or by using them in combination with other compounds. However, in practice, none of these compounds completely meet the requirements as regards producing a satisfactory increase in sensitivity without concomitant increases in fog or poor keeping qualities.

The object of the present invention is to provide new chemical sensitizers which do not suffer the above disadvantages. Another object is to provide photographic silver halide emulsions having increased sensitivity and satisfactory keeping qualities.

We now have found that the sensitivity of an ordinary photographic silver halide emulsion can be substantially increased by incorporating therein spirocyclic, sulfurcontaining quaternary salts of the following formula:

wherein X=a single chemical bond, a sulfur atom, a methylene group, a sulfonyl group or the quaternary nitrogen atom of a spirocyclically bound thiomorpholine ring;

A=any anion, such as a halogen ion, preferably bromide, or a tosylate anion.

Particular utility is exhibited by the following The spirocyclic quaternary salts to be used according to the invention may be prepared in known manner.

Thiomorpholine which can be prepared, for example, by the process described in German specification 1,104,- 513, is a particularly useful starting material.

The preparation of compound of the above general formula in which the group X is a methylene group, is described in detail below.

COMPOUND I 6-azonia-9-sulfa-spiro-5,S-undecane bromide COMPOUND II 6-azonia-3,9-sulfa-spiro-5,S-undecane bromide-9-dioxide 23 g. of neutral thiomorpholine hydrochloride are dissolved in a mixture of 50 ml. of ethanol and 10 ml. of water, and after the addition of a small amount (about 15 droplets) of triethylamine as catalyst 19.8 g. of divinylsulfon are added dropwise. Reaction occurs under spontaneous heating and precipitation of colorless crystals. The reaction mixture is left standing over night and suction filtered. 32.3 g. of colorless crystals are obtained. Melting point under decomposition 262 C.

The compounds according to the invention can be used in any silver halide emulsions. Silver halides which may be used are silver chloride, silver bromide or mixtures thereof, if desired with a small amount of silver iodide of up to mols percent. The silver halides can be dispersed in the usual hydrophilic compounds, for example, in carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts, esters or amides, and preferably in gelatin.

The preparation of photographic silver halide emulsions includes 3 separate steps:

(1) emulsification and physical ripening which is also called Ostwald ripening; (2) the freeing of the emulsion of excess water soluble salts, usually by washing with water and drying, and (3) the after ripening which is also called chemical ripening to obtain increased emulsion speed or general sensitivity.

The sensitizer of the present invention can be added to the emulsion before, during or after the chemical ripening or they can be added immediately prior to the casting. In many cases it has proved advantageous to add the chemical sensitizer of the present invention before or during the after-ripening.

The particular quantity of the sensitizers of the invention used in a given emulsion can vary, depending upon the effects desired, the silver content of the emulsion, the silver halide composition etc. The amount used is also dependent upon the particular stage at which the sensitizer was added during the preparation of the emulsion. Generally they are added in amounts of 0.003 to 3 g. preferably 0.003 to 0.6 g. per mol of silver halide. If added prior to casting after the after-ripening, the amount used is slightly higher for instance 0.03-3.0 g. per mol of silver.

The sensitizers can be dissolved in water or a solvent miscible with water or a mixture of water and water miscible solvents, and added in such form to the emulsion. The solvent is not critical and should be selected so that it should have no harmful effect on the photographic properties of the silver halide emulsion.

The optimum amount for any sensitizer of the present invention can be determined for any particular emulsion by running a series of comparison tests in which the quantity of the sensitizer is varied over a given range. Exposure of the emulsion containing the sensitizer in a manner well known and measuring of the sensitivity in conventional apparatuses will reveal most advantageous concentrations. Such technic is well understood by those skilled in the art.

The photographic emulsion in which the sensitizers according to the invention are used, can contain additional chemical sensitizers customarily employed. They can be sensitized, for example, with sulfur compounds as referred to, e.g., in the book The Theory of the Photographic Process by Mees (1954), pages 149-161.

The emulsions can also be chemically sensitized with salts of noble metal such as gold, ruthenium, rhodium, palladium, iridium and platinum, used in amounts below that which produce any substantial fog. Representative compounds are ammonium chloropalladate, potassium chlorop latinate, potassium chlorolaurate, auric trichloride and the like. The emulsions can be sensitized with reducing agents, stannous salts or polyamines and the like.

According to a preferred embodiment of the invention, the spirocyclic quartemary salts are used in combination with chemical sensitizers of the polyalkylene oxide type. Suitable compounds of this type are, for example,- those of the following formula:

R=a hydrogen atom or an alkyl group with preferably up to 18 carbon atoms such as an ethyl or dodecyl,

an acyl group, preferably an acyl radical of an aliphatic carboxylic acid having up to 18 carbon atoms such as lauric acid or oleic acid, or an aryl group such as phenyl or p-dodecylphcnyl;

n=an integer between 8 and 200. Molecular weights of from 1500 to 10,000 are preferred for the polyethylene oxides, examples of which are described in US. Patents 2,240,472 and 2,400,532.

Other suitable chemical sensitizers are derivatives of phosphoric acid which contain polyalkylene oxide chains. Suitable products have been described in British patent specifications 1,045,183 and 1,045,184 or French patent specifications 1,396,860 and 1,423,680.

Such compounds are condensation products of spirocyclic pentaerythritol-di-phosphoric acid monohalides and polyethylene glycols containing about 3 to 100 ethylene oxide units in the molecule. They correspond to the following formula:

R =a hydrogen atom, an alkyl, aryl or aralkyl group and R =an alkyl, aryl or aralkyl group;

R and R may together represent the ring members required for completing a 5- or 6-membered heterocyclic ring;

m=an integer between 2 and 100 preferably between 3 and p=an integer from 0 to and q=an integer from 1 to 5.

O CID-CH2) wherein The spirocyclic quaternary salts according to the invention may also be used advantageously in combination with the cross-linked or non-cross-linked water-soluble quaternated products of tertiary polyamines with bifunctional poly-alkylene oxide derivatives. These quaternated products have been described in German patent application A 50,595.

A particularly advantageous increase in sensitivity is obtained by adding a thiazolidone stabilizer of the type described in German patent specification 1,209,425 to the combination of the compounds according to the invention with a polyalkylene oxide.

Furthermore, the emulsions may contain stabilizers such as homopolar or salt-type compounds of mercury which contain aromatic or heterocyclic rings (e.g., mercaptotriazoles), simple mercury salts, sulfonium-mercury double salts and other mercury compounds. Other suitable stabilizers are azaindenes, preferably tetra or pentaazaindenes, especially those substituted with hydroxyl or amino groups. Such compounds have been described by Birr, Z. Wiss., Phot, 47, 258(1962). Other suitable stabilizers include heterocyclic mercapto compounds such as phenylmercapto-tetrazole, quaternary benzthiazole derivatives and benztriazoles.

aldehyde which contain a carboxyl group, e.g., mucobromic acid diketones, methane sulfonic acid ester and dialdehydes.

LNEC-CHzOHz-O-CHaCH:

The compounds according to the invention may also be added to emulsions containing color couplers.

In addition to being added to an emulsion, they may also be added to the developer.

EXAMPLE 1 To a silver iodobromide gelatine emulsion which contained 60 g. of silver in the form of silver halide per liter, which emulsion had a silver iodide content of 6 mols percent were added 600 mg. of saponin as wetting agent,

200 mg. of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene as stabilizer and 10 ml. of a 10% aqueous solution of formaldehyde.

This emulsion was divided into three equal parts and the following compounds were added to the separate parts:

Sample A: Control samplewithout additive Sample B: 240 mg. of 6-azonia-9-sulfaspiro-[5,5]-undecane bromide (Compound I) per liter of emulsion;

Sample C: 480 mg. of the same compound per liter of emulsion.

The casting solutions obtained were applied onto a cellulose acetate support, exposed behind a grey step wedge in a conventional sensitometer and developed at C. in a developer which had the following composition:

Grams Anhydrous sodium sulfite 70 Borax 7 Hydroquinone 3.5 p-Monomethyl-aminophenol 3.5 Sodium citrate 7 Potassium bromide 0.4

Made up to 1 liter with water.

The results of the sensitometric comparison tests are shown in the following table (where B is the sensitivity on the DIN scale and S is the fog level):

The same emulsion as in Example 1 was divided into 9 equal parts and the following compounds were added to the separate parts:

Sample A: Control samplewithout additive Sample B: 480 mg. per liter of emulsion of the sensitiser of the following formula (described in German patent No. 1,178,297)

Sample C: 480 mg. per liter of emulsion of ionic polyalkylene oxide derivative of the following formula (according to German patent application A 50,595).

e CHnCHz-O-CHqCHz-CEN 2 Tosylate Sample D: 240 mg. per liter of emulsion of 6 -azonia-9- sulfaspiro-[5,5]-undecane-bromide (Compound I) and 240 mg. per liter of emulsion of the polyethylene glycol phosphoric acid ester used in Sample B.

Sample E: 480 mg. per liter of emulsion of 6-azonia-9- sulfaspiro-[5,5]-undecane-bromide (Compound I) and 480 mg. per liter of emulsion of the polyethylene glycol phosphoric acid ester used with Sample B.

Sample F: 240 mg. per liter of emulsion of 6-azonia-9- sulfaspiro-[5,5]undecane bromide (Compound I) and 240 mg. per liter of the chemical sensitizer already used with Sample C.

Sample G: 480 mg. of each of the compounds used in Sample F.

Sample H: 240 mg. per liter of emulsion of 6-azonia-9- sulfaspiro-[5,5]-undecane bromide (Compound I) and 240 mg. per liter of the chemical sensitizer used with Sample C and 480 g. per liter of emulsion of a thiazolidone stabilizer of the following formula (according to German patent specification 1,209,425):

I .m S N-C'Ha ll (EH.

Sample I: 240 mg. per liter of emulsion of 6-azonia-9- sulfaspiro-[5,5]-undecane bromide, 240 mg. of the polyethylene glycol phosphoric acid ester used with sample B per liter of emulsion and 480 mg. per liter \of emulsion of the thiazolidone stabilizer of the following formula (according to German patent specification 1,209,425):

The samples were applied onto a cellulose acetate support, exposed and the dried layer developed as described in Example 1. The following table shows the sensitometric properties of the various emulsions:

TABLE 2 10 min. development 20 min. development E 'y S E 7 S 0. 70 0. 09 Control 1. 20 0. 10

7 EXAMPLE 3 40 mg. per liter of the panchromatic sensitizer of the following formula CzHs Were added to an emulsion as described in Example 1, and the emulsion was then divided into four equal parts. The following compounds were added to the separate parts:

Sample A: Control samplewithout additive Sample B: 400 mg. per liter of emulsion of 6-azonia-9- sulfa-spiro-[5,5]-undecane bromide (Compound I) Sample C: 240 mg. per liter of emulsion of 6-azonia-9- sulfa-spiro-[5,5]-undecane-bromide (Compound I) and 250 mg. per liter of emulsion of the chemical sensitizer used with Sample C of Example 2.

Sample D: 240 mg. per liter of emulsion of 6-azonia-9- sulfa-spiro-[5,51-undecane bromide (Compound I) and 240 mg. per liter of emulsion of the compound of the type described in German patent specification 1,178,297 which was used in Example 2.

The samples were applied onto a cellulose acetate Support and the dried layer exposed and developed as in Example 1.

TABLE 3 10 min. development 20 min. development E 'y S E 'y S 65 0.12 Control. 1 0.05 0.65 0.03 +2.0 0 95 0.07 0 80 0.04 +3. 1 25 0.09 0 70 0.04 +2 1 0.12

EXAMPLE 4 A silver iodobromide emulsion containing 6 mols percent of silver iodide was prepared according to common practice and divided into three parts ready for chemical ripening. The usual ripening additives, such as sulfur compounds, for example sodium thiosulfat and gold salts and after-ripening gelatin were added to the separate parts. In addition, the following compounds were added to the three parts.

Sample A: Control samplewithout additive.

Sample B: 80 mg. per liter of emulsion of 6-azonia-9- sulfa-spiro-[5,5]-undecane bromide (Compound I).

Sample C: 160 mg. per liter of emulsion of 6-azonia-9- sulfa-spiro-[5,5]-undecane bromide (Compound I).

The after-ripening was completed and the samples applied onto a support of polyalkylene terephthalate. The dried layers were developed as described in Example 1.

TABLE 4 10 min. development 20 min. development E 7 S E 7 S Sample:

A ControL 0. 0.10 Control. 0. 0. 16 B +1. 0.70 0.12 +3.0 0.80 0.15 O +2.0 0. 70 0.12 +1.5- 0.00 0.19

EXAMPLE 5 The emulsion of Example 1 was divided into 4 equal parts and the following compounds were added to the 4 samples:

Sample A: Control samplewithout additive.

Sample B: 240 mg. of compound II per liter of emulsion.

Sample C: 240 mg. per liter of emulsion of the sensisitizer of Sample C of Example 2.

Sample D: 240 mg. per liter of emulsion of each of compound H and the sensitizer of Sample C.

The samples were applied onto a cellulose acetate sup port and the dried layer exposed and processed as described in Example 1.

TABLE 5 10 min. development E 'y S TABLE 6 10 min. development;

E 'y S Control.

We claim: 1. A light-sensitive material comprising at least one silver halide emulsion layer which contains a sensitivityincreasing amount of a chemical sensitizer of the following formula:

H7 H7 H2 H1 0-0 0- wherein X represents a single chemical bond, a sulfur atom, a methylene group, a sulfonyl group or the quaternary nitrogen atom of a spirocyclically bound thiomorpholine ring; and A stands for an ion. 2. A light-sensitive material as defined in claim 1 in which the cation of the chemical sensitizer has the following formula:

0112-052 Hit-Cg:

wherein R represents hydrogen or alkyl, acyl or phenyl and n an integer from 8 to 200. 5. A lightsensitive material as defined in claim 3 in which the sensitizer of the polyethylene oxide series has the following formula:

0 0-011 Rlail L 0Cfi2 wherein R represents hydrogen or an alkylene oxide chain containing from 3 to alkylene oxide units; m is an integer from 3 to 100 and x is an integer from 1 to 10. 6. A light-sensitive material as defined in claim 1 which in addition contains a stabilizing amount of a thiazolidone stabilizer.

References Cited UNITED STATES PATENTS 2,976,250 3/1961 Walford 96-109 XR 3,210,192 10/1965 Willems et a1 96110 XR NORMAN G. TORCHIN, Primary Examiner J. R. EVERETT, Assistant Examiner US. Cl. X.R. 96-109 

